Comet crunch

NEARLY 90 per cent of the 104 comets that the SOHO spacecraft has discovered close to the Sun in the past four years are small fragments of a single giant comet.

Astronomers believe they are descendants of a giant comet that broke up, possibly the one observed by the Greek historian Ephorus in 372 BC. The fragments break up every time their 800-year orbit takes them past the Sun, says Doug Biesecker, a SOHO scientist at the NASA Goddard Space Flight Center in Greenbelt, Maryland.

Biesecker believes the fragments broke into icy chunks measuring less than 50 metres in diameter the last time the comet's remains passed close to the Sun. This time as they came within 700 000 kilometres of the Sun, says Biesecker, "they've all just completely evaporated".

To continue reading this article, subscribe to receive access to all of newscientist.com, including 20 years of archive content.

To continue reading this article, log in or subscribe to New Scientist

App + web

Web

Smartphone

Tablet

$25.99 - Save 65%

12 issues for $2.17 per issue

with continuous service

Print + web

Print

Web

$28.99 - Save 61%

12 issues for $2.42 per issue

with continuous service

Print + app + web

Print

Web

Smartphone

Tablet

$39.99 - Save 73%

12 issues for $3.33 per issue

with continuous service

Web

Web only

$49.99

30 day web pass

Prices may vary according to delivery country and associated local taxes.